Video adapter circuit for detection of analog video scanning formats
First Claim
1. A method of detecting a format of an analog video signal having a horizontal sync signal and a vertical sync signal the method comprising steps of:
- a. counting a first number of pulses of a clock signal occurring when the horizontal sync signal is a low voltage and counting a second number of pulses of the clock signal occurring when the horizontal sync signal is a high voltage;
b. determining whether the first number or the second number is within a first predetermined range of values;
c. counting a third number of pulses of the horizontal sync signal occurring when the vertical sync signal is a low voltage and counting a fourth number of pulses of the horizontal sync signal occurring when the vertical sync signal is a high voltage;
d. determining whether the third number or the fourth number is within a second predetermined range of values; and
e. determining whether the first number or the second number is equivalent to one of a plurality of numbers of pixels in a horizontal line associated with a video format.
1 Assignment
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Accused Products
Abstract
A video adapter circuit for adapting analog video signals provided by a personal computer system designed to drive a CRT display monitor into signals appropriate for driving a flat panel display monitor. The video adapter circuit accepts analog video and synchronizing signals in any one of several scanning formats commonly utilized in personal computer systems and automatically detects the scanning format of the signals. An oscillator generates a clock signal that is synchronized with the HSYNC signal generated by the personal computer system. Each of the analog RGB video signals are amplified by a video amplifier and sampled, according to the clock signal, by an analog-to-digital converter. A controller circuit compresses the sampled video signals and stores the compressed data in a dual-port video frame memory at a rate determined by the scanning format. The compressed data is retrieved and decompressed from the video frame memory at a rate determined by the requirements of the flat panel display monitor and converted into a format appropriate for driving the flat panel display monitor. If the received video signals have a resolution that is lower than the resolution provided by the flat panel display monitor, the video adapter circuit automatically expands the image to fill the entire image area of the flat panel display monitor. An on-screen menu provides a user interface for the video adapter circuit, including an ability to adjust the brightness and contrast ratio of the image displayed on the flat panel display monitor by adjusting the dc level and the gain of the video amplifier. In addition, the horizontal and vertical position of the displayed image can be adjusted.
78 Citations
22 Claims
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1. A method of detecting a format of an analog video signal having a horizontal sync signal and a vertical sync signal the method comprising steps of:
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a. counting a first number of pulses of a clock signal occurring when the horizontal sync signal is a low voltage and counting a second number of pulses of the clock signal occurring when the horizontal sync signal is a high voltage; b. determining whether the first number or the second number is within a first predetermined range of values; c. counting a third number of pulses of the horizontal sync signal occurring when the vertical sync signal is a low voltage and counting a fourth number of pulses of the horizontal sync signal occurring when the vertical sync signal is a high voltage; d. determining whether the third number or the fourth number is within a second predetermined range of values; and e. determining whether the first number or the second number is equivalent to one of a plurality of numbers of pixels in a horizontal line associated with a video format. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of detecting a format of an analog video signal having a horizontal sync signal and a vertical sync signal the method comprising steps of:
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a. counting a first number of pulses of a clock signal occurring when the horizontal sync signal is a low voltage and counting a second number of pulses of the clock signal occurring when the horizontal sync signal is a high voltage; b. determining whether the first number or the second number is within a first predetermined range of values; c. counting a third number of pulses of the horizontal sync signal occurring when the vertical sync signal is a low voltage and counting a fourth number of pulses of the horizontal sync signal occurring when the vertical sync signal is a high voltage; d. determining whether the third number or the fourth number is within a second predetermined range of values; and e. determining whether the third number or the fourth number is equivalent to one of a plurality of numbers of horizontal lines associated with a video format. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of detecting a format of an analog video signal having a horizontal sync signal and a vertical sync signal, the method comprising steps of:
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a. determining a polarity of the horizontal sync signal; b. determining a polarity of the vertical sync signal; and c. when the polarity of the horizontal sync signal and the polarity of the vertical sync signal do not uniquely identify the format, performing a step of detecting the format by determining a number of pixels in a horizontal line. - View Dependent Claims (16, 17, 18)
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19. A method of detecting a format of an analog video signal having a horizontal sync signal and a vertical sync signal, the method comprising steps of:
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a. determining a polarity of the horizontal sync signal; b. determining a polarity of the vertical sync signal; and c. when the polarity of the horizontal sync signal and the polarity of the vertical sync signal do not uniquely identify the format, performing a step of detecting the format by determining a number of horizontal lines. - View Dependent Claims (20, 21, 22)
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Specification